The use of dialkylmagnesium or alkylmagnesium iodide in combination with barium ethoxide particularly additionally with 1,1-diphenylethylene as initiators of polymerization of butadiene to give polybutadienes having a trans-1,4 content as high as 78% and a vinyl content of 6% has been disclosed by the Physico-Chemical Research Institute, Polymer Science U.S.S.R., 18(9), 2325 (1976). This paper, also, shows that a catalyst system of magnesium and barium tert-butoxide gave a polybutadiene with only 45% trans-1,4 content (200 hours polymerization time and conversion of only 10%).
U.S. Pat. No. 3,846,385 (U.S. Pat. No. 3,903,019 is a division of the same) shows the preparation of random butadiene-styrene copolymers having a high trans-1,4 content and a vinyl content of 9%. The trans-1,4 content increased as the mol ratio of Ba(t-BuO).sub.2 /(Bu).sub.2 Mg decreased with little variation in either the vinyl content or heterogeneity index. A copolymer exhibited a well defined crystalline melting temperature at 32.6.degree. C. by differential thermal analysis (DTA). The Molecular Weight Distribution (MWD) of these copolymers was characterized by having heterogeneity indices (M.sub.w /M.sub.n) ranging from 1.4 to 2.2. Polybutadienes made with these catalysts exhibited a trans-1,4 content as high as 78%. No polymerization or copolymerization occurred when only one of the catalyst components was used alone.
Polymerization of butadiene with some cyclization in hexane or toluene at 100.degree. C. using Bu.sub.2 Mg-BuMgI is reported in "Chem. Abstracts," 1963, 4045e.
Polymerization of butadiene using Ba(OEt).sub.2 with Et.sub.2 Mg, (C.sub.4 H.sub.9).sub.3 Mg.sub.2 I or (C.sub.6 H.sub.13).sub.2 Mg is reported in "Chem. Abstracts," Vol. 84, 1976, 151067n.
Dialkylmagnesium compounds and their complexes with organoaluminum or with organolithium compounds are said to be cocatalysts with Ziegler based catalyst systems (transition metal compounds) for the polymerization of dienes and olefins. This has been described by Texas Alkyls (Product Data Sheet MAGALA-6E) and Lithium Corporation of America (Product and Technical Bulletin on "Polymerization Using Magnesium Alkyl Catalysts," 1978).
British Pat. No. 1,531,085 discloses in the working examples the preparation of polybutadienes and butadiene-styrene copolymers having inherent viscosities of 0.8 to 5, t rans-1,4 contents of 34 to 90% and vinyl contents of 2 to 38%. A two component catalyst is used. As shown by the working examples the first component can comprise a Ba[Al(C.sub.2 H.sub.5).sub.4 ].sub.2, Ba[Al(C.sub.2 H.sub.5).sub.3 OR].sub.2 where R is a nonyl phenate radical, LiAl-(C.sub.2 H.sub.5).sub.4, NaAl(C.sub.2 H.sub.5).sub.4, KAl(C.sub.2 H.sub.5).sub.4, LiAl(C.sub.2 H.sub.5).sub.3 OCH(CH.sub.3).sub.2, LiOAl(C.sub.2 H.sub.5).sub.2 compound and so forth. The second component is a polar compound or the like such as tetrahydrofuran, methanol, water, tetramethylethylene diamine, acetone, barium nonyl phenate, lithium isopropylate, Natert-amylate, acetonitrile and so forth. The molar ratio between the polar compound and the organic compound of metal of Group IIIA such as Al is from 0.01 to 100.
U.S. Pat. No. 4,079,176 discloses a process for polymerizing dienes and for copolymerizing dienes and vinyl aromatic compounds with a catalyst composition comprising (A) an organolithium and (B) a compound having the formula EQU M.sup.a (M.sup.b R.sup.1 R.sup.2 R.sup.3 R.sup.4).sub.2 or M.sup.a [M.sup.c (R.sup.1).sub.4 ]
where M.sup.a is Ba, Ca, Sr or Mg; M.sup.b is B or Al; M.sup.c is Zn or Cd; R.sup.1, R.sup.2 and R.sup.3 are alkyl or aralkyl radicals; R.sup.4 is an alkyl, aralkyl radical or OR.sup.5 where R.sup.5 is an alkyl or aralkyl radical. The working examples show the polymerization of BD and copolymerization of BD with STY to provide polymers exhibiting intrinsic viscosities of 0.81 to 1.6, trans-1,4 contents of 76 to 85% and vinyl contents of 2 to 6%.
U.S. Pat. No. 4,080,492 discloses a method for polymerizing BD or copolymerizing BD and vinyl aromatic compounds using a catalytic composition of (a) an organolithium compound and (b) a cocatalyst system which comprises a Ba or Sr compound and an organometallic compound from Groups IIB or IIIA like zinc or aluminum. Examples of the Ba or Sr compounds are their hydrides, organic acid salt, alcoholates, thiolates, phenates, alcohol and phenol acid salts, betadiketonates and so forth. Table VIIA shows the use of barium tertiobutanolate. Examples of the Group IIB and IIIA materials are diethylzinc, diethyl cadmium, triethyl aluminum and so forth. The working examples for the preparation of polymers of BD and copolymers of BD and STY show .eta. of 0.34 to 2.15, trans-1,4 of 61 to 90% and vinyl contents of 2.4 to 9%.
U.S. Pat. No. 4,092,268 is similar to U.S. Pat. No. 4,080,492 but it includes isoprene and shows in Examples 11 and 12 the polymerization of isoprene and the copolymerization of isoprene and styrene.
British Pat. No. 1,516,861 has a somewhat similar disclosure to that of U.S. Pat. No. 4,080,492 and both are based on the same French patent application. The U.S. case apparently deleted reference to the polymerization of isoprene.
British Pat. No. 1,525,381 (patent of addition to Br. 1,516,861, above) discloses a process for polymerizing butadiene and copolymerizing butadiene and styrene using a catalyst composition of (a) an organolithium, (b) a compound of barium, strontium or calcium, (c) an organometallic compound of a metal of Group IIB or IIIA and (d) an amino or ether alcoholate of an alkali metal. An example of (a) is n-butyl lithium; of (b) is Ca, Ba or Sr alcoholate or phenate particularly barium nonyl phenate; of (c) is EQU (C.sub.2 H.sub.5).sub.2 Zn, (C.sub.2 H.sub.5).sub.3 Al or (i-butyl).sub.3 Al; EQU and of (d) is C.sub.2 H.sub.5 (OCH.sub.2 CH.sub.2).sub.2 OLi, (C.sub.2 H.sub.5).sub.2 NCH.sub.2 CH.sub.2 OLi or CH.sub.2 (OCH.sub.2 CH.sub.2).sub.2 ONa.
The working examples for the polybutadienes and butadiene-styrene copolymers made show inherent viscosities of 0.9 to 2.4, trans-1,4 contents of 80 to 90% and vinyl contents of 2 to 4%. For Example 2 it is stated that the green strength test on the black loaded uncured copolymers showed a similar resistance to elongation to that of natural rubber.
A class of crystallizing elastomers based on butadiene containing sufficient amounts of the trans-1,4 structure to crystallize has been disclosed in U.S. Pat. No. 3,992,561 (divisional U.S. patents of the same Nos. 4,020,115; 4,033,900 and 4,048,427 have the same disclosure in the specification). The catalyst for the preparation of these polymers comprises an alkyl lithium compound such as n-butyl lithium and a barium t-alkoxide salt such as a barium salt of t-butanol and water. The polymerization temperature, the nature of the solvent and the mole ratio of the catalyst components and its concentration were found to control the polybutadiene microstructure and molecular weight. It is stated that the crystalline melting temperature of the high trans polybutadienes can be depressed near or below room temperature by the copolymerization of styrene, still permitting the rubber to undergo strain induced crystallization. The butadiene polymers and butadiene-styrene copolymers exhibited green strength and tack strength. A high trans polybutadiene exhibited a broad bimodal molecular weight distribution. This patent discloses in the working examples for the invention polybutadiene and butadiene-styrene copolymers exhibiting intrinsic viscosities of 1.43 to 7.39, trans-1,4 contents of 63 to 80.4% and vinyl contents of 6 to 9%.
Copending U.S. Patent Application Ser. No. 077,428 filed Sept. 20, 1979, now U.S. Pat. No. 4,260,712 (U.S. Pat. No. 4,260,519 is a division), discloses an improved barium t-alkoxide salt for use with a hydrocarbon lithium compound for the preparation of polybutadiene and butadiene-styrene copolymers. It shows in the working examples for polybutadiene and butadiene-styrene copolymers intrinsic viscosities of from 3.74 to 7.68, trans-1,4 contents of 73 to 82% and vinyl contents of 6 to 13%.
"Gummi-Asbest-Kunststoffe," pages 832 to 842, 1962 reviews several catalyst systems for polymerizing unsaturated monomers and discusses the properties of several polymers. On page 835, Table 4, it discloses the use of a catalyst system of R.sub.2 Mg and RMgHal to polymerize butadiene to make a polybutadiene having 45-49 trans-1,4 units.